The invention relates to the field of anticancer chemotherapy, and cytoprotective agents administered before, during or after anticancer chemotherapy to protect the normal cells of the patient from the cytotoxic effects of anticancer chemotherapeutics.
Experimental chemotherapy has been the mainstay of treatment offered to patients diagnosed with surgically unresectable advanced cancers, or cancers refractory to standard chemotherapy and radiation therapy. Of the more effective classes of drugs, curative properties are still limited. This is because of their relatively narrow therapeutic index, restricted dosage, delayed treatments and a relatively large proportion of only partial tumor reductions. This state is usually followed by recurrence, increased tumor burden, and drug resistant tumors.
Several cytoprotective agents have been proposed to enhance the therapeutic index of anticancer drugs. For methotrexate toxicity, such agents include asparaginase, leucovorum factor, thymidine, and carbipeptidase. Because of the extensive use of anthracyclines, specific and non-specific cytoprotective agents have been proposed which have varying degrees of efficacy; included are corticosteroids, desrazoxane and staurosporin. The latter is of interest in that it includes a G1/S restriction blockade in normal cells. (Chen et al., Proc AACR 39:4436A, 1998).
Cisplatin is widely used and has a small therapeutic index which has spurred investigation and search of cytoprotectants. Among the cytoprotectants for cisplatin with clinical potential are mesna, glutathione, Na-thiosulfate, and amifostine (Griggs, Leuk. Res. 22 Suppl 1:S27-33, 1998; List et al., Semin. Oncol. 23(4 Suppl 8):5863, 1996; Taylor et al., Eur. J. Cancer 33(10):1693-8, 1997). None of these or other proposed cytoprotectants such as oxonic acid for fluoropyrimidine toxicity, or prosaptide for paclitaxel PC12 cell toxicity, appears to function by a mechanism which renders normal replicating cells into a quiescent state.
What is needed are cytoprotective agents which are effective in protecting animals, inclusive of humans, from the cytotoxic side effects of chemotherapeutic agents.
Unrelated to the foregoing, styryl sulfones having pharmaceutical utility as anticancer agents have been reported in WO/99/18068, the entire disclosure of which is incorporated herein by reference. The compounds inhibit tumor cell growth by inducing tumor cell death without killing normal cells. The styryl sulfones are effective in a broad range of tumor types. Without wishing to be bound by any theory, it is believed that the styryl sulfones affect the Mitogen Activated Protein Kinase (MAPK) signal transduction pathway, thereby affecting tumor cell growth and viability.
It is an object of the invention to provide compositions and methods for protecting animals, inclusive of humans, from the cytotoxic side effects of chemotherapeutic agents, particularly mitotic phase cell cycle inhibitors and topoisomerase inhibitors, used in the treatment of cancer and other proliferative disorders.
It is an object of the invention provide a method for treating cancer or other proliferative disorder which reduces or eliminates cytotoxic effects on normal cells.
It is an object of the invention to enhance the effects of chemotherapeutic agents, particularly mitotic phase cell cycle inhibitors and topoisomerase inhibitors, used for the treatment of cancer or other proliferative disorders.
It is an object of the present invention to provide a therapeutic program for treating cancer or other proliferative disorder which includes administration of a cytoprotective compound prior to administration of a chemotherapeutic agent, which cytoprotective compound induces a reversible cycling quiescent state in non-tumored tissues.
It is an object of the invention to provide a method for safely increasing the dosage of chemotherapeutic agents, particularly mitotic phase cell cycle inhibitors and topoisomerase inhibitors, used in the treatment of cancer and other proliferative disorders.
According to the present invention, a method for protecting an animal from cytotoxic side effects of the administration of a mitotic phase cell cycle inhibitor or a topoisomerase inhibitor comprises administering to the animal, in advance of administration of the aforesaid inhibitor, an effective amount of at least one cytoprotective xcex1,xcex2 unsaturated aryl sulfone compound. The term xe2x80x9canimalxe2x80x9d is meant to embrace human beings, as well as non-human animals.
By xe2x80x9cxcex1,xcex2 unsaturated aryl sulfone compoundxe2x80x9d as used herein is meant a chemical compound containing one or more xcex1,xcex2 unsaturated aryl sulfone groups: 
wherein Q2 is substituted or unsubstituted aryl, and the hydrogen atoms attached to the xcex1 and xcex2 carbons are optionally replaced by other chemical groups.
By xe2x80x9csubstitutedxe2x80x9d means that an atom or group of atoms has replaced hydrogen as the substituent attached to a ring atom. The degree of substitution in a ring system may be mono-, di-, tri- or higher substitution.
The term xe2x80x9carylxe2x80x9d, alone or in combination, means a carbocyclic aromatic system containing one, two, or more rings wherein such rings may be attached together in a pendent manner or may be fused. The term xe2x80x9carylxe2x80x9d is intended to include not only aromatic systems containing only carbon ring atoms but also systems containing one or more non-carbon atoms as ring atoms. Such systems may be known as xe2x80x9cheteroarylxe2x80x9d systems. The term xe2x80x9carylxe2x80x9d is thus deemed to include xe2x80x9cheteroarylxe2x80x9d. Heteroaryl groups include, for example, pyridyl, thienyl, furyl, thiazolyl, pyrrolyl, and thienyl-1,1-dioxide. The heterocyclic radical may be substituted or unsubstituted. The term xe2x80x9carylxe2x80x9d is not limited to ring systems with six members.
According to one embodiment, the xcex1,xcex2 unsaturated aryl sulfone group is a styryl sulfone group: 
wherein the hydrogen atoms attached to the xcex1 and xcex2 carbons are optionally replaced by other chemical groups, and the phenyl ring is optionally substituted.
By xe2x80x9cstyryl sulfonexe2x80x9d or xe2x80x9cstyryl sulfone compoundxe2x80x9d or xe2x80x9cstyryl sulfone therapeuticxe2x80x9d as used herein is meant a chemical compound containing one or more such styryl sulfone groups.
According to another embodiment of the invention, a method of treating an individual for cancer or other proliferative disorder is provided. The method comprises administering to the animal an effective amount of at least one mitotic phase cell cycle inhibitor or topoisomerase inhibitor, and administering before the inhibitor, an effective amount of at least one cytoprotective xcex1,xcex2 unsaturated aryl sulfone compound.
By xe2x80x9ceffective amountxe2x80x9d of the mitotic phase cell cycle inhibitor or topoisomerase inhibitor is meant an amount of said inhibitor effective in killing or reducing the proliferation of cancer cells in a host animal. By xe2x80x9ceffective amountxe2x80x9d of the cytoprotective xcex1,xcex2 unsaturated aryl sulfone compound is meant an amount of compound effective to reduce the toxicity of the mitotic phase cell cycle inhibitor or topoisomerase inhibitor on normal cells of the animal.
The xcex1,xcex2 unsaturated aryl sulfone cytoprotective compounds are characterized by cis-trans isomerism resulting from the presence of a double bond. Stearic relations around a double bond are designated as xe2x80x9cZxe2x80x9d or xe2x80x9cExe2x80x9d. Both configurations are included in the scope of xe2x80x9cxcex1,xcex2 unsaturated aryl sulfonexe2x80x9d: 
According to one embodiment, the xcex1,xcex2 unsaturated aryl sulfone compound is a compound of the formula I: 
wherein:
n is one or zero;
Q1 and Q2 are, same or different, are substituted or unsubstituted aryl.
Preferably, n in formula I is one, that is, the compounds comprise xcex1,xcex2 unsaturated benzylsulfones, e.g. styryl benzylsulfones.
According to one sub-embodiment, n is preferably one and:
Q1 is selected from the group consisting of substituted and unsubstituted phenyl, 1-naphthyl, 2-naphthyl, 9-anthryl and an aromatic radical of formula II: 
xe2x80x83wherein
n1 is 1 or 2,
Y1 and Y2 are independently selected from the group consisting of hydrogen, halogen, and nitro, and
X1 is selected from the group consisting of oxygen, nitrogen, sulfur and 
Q2 is selected from the group consisting of substituted and unsubstituted phenyl, 1-naphthyl, 2-naphthyl, 9-anthryl and an aromatic radical of formula III: 
xe2x80x83wherein
n2 is 1 or 2,
Y3 and Y4 are independently selected from the group consisting of hydrogen, halogen, and nitro, and
X2, X3 and X4 are independently selected from the group consisting of carbon, oxygen, nitrogen, sulfur and 
provided that not all of X2, X3 and X4 may be carbon.
According to one preferred embodiment according to formula 1, Q1 and Q2 are selected from substituted and unsubstituted phenyl.
Preferred compounds where Q1 and Q2 are selected from substituted and unsubstituted phenyl comprise compounds of the formula IV: 
wherein:
R1 through R10 are independently selected from the group consisting of hydrogen, halogen, C1-C8 alkyl, C1-C8 alkoxy, nitro, cyano, carboxy, hydroxy, phosphonato, amino, sulfamyl, acetoxy, dimethylamino(C2-C6 alkoxy), C1-C6 trifluoroalkoxy and trifluoromethyl.
In one embodiment, compounds of formula IV are at least di-substituted on at least one ring, that is, at least two of R1 through R5 and/or at least two of R5 through R10, are other than hydrogen. In another embodiment, compounds of formula IV are at least trisubstituted on at least one ring, that is, at least three of R1 through R5 and/or at least three of R5 through R10, are other than hydrogen.
In one embodiment, the cytoprotective compound has the formula V: 
wherein R1, R2, R3 and R4 are independently selected from the group consisting of hydrogen, halogen, C1-C8 alkyl, C1-C8 alkoxy, nitro, cyano, carboxy, hydroxy and trifluoromethyl.
According to a particularly preferred embodiment of the invention, the cytoprotective compound is according to formula V, and R1 and R2 are independently selected from the group consisting of hydrogen, chlorine, fluorine, bromine, cyano, and trifluoromethyl; and R3 and R4 are independently selected from the group consisting of hydrogen, chlorine, fluorine and bromine.
Preferred compounds according to formula V having the E-configuration include, but are not limited to, (E)-4-fluorostyryl-4-chlorobenzylsulfone; (E)-4-chlorostyryl-4-chlorobenzylsulfone; (E)-2-chloro-4-fluorostyryl-4-chlorobenzylsulfone; (E)-4-carboxystyryl-4-chlorobenzylsulfone; (E)-4-fluorostyryl-2,4-dichlorobenzylsulfone; (E)-4-fluorostyryl-4-bromobenzylsulfone; (E)-4-chlorostyryl-4-bromobenzylsulfone; (E)-4-bromostyryl-4-chlorobenzylsulfone; (E)-4-fluorostyryl-4-trifluoromethylbenzylsulfone; (E)-4-fluorostyryl-3,4-dichlorobenzylsulfone; (E)-4-fluorostyryl-4-cyanobenzylsulfone; (E)-2,4-dichloro-4-chlorobenzylsulfone; and (E)-4-chlorostyryl-2,4-dichlorobenzylsulfone.
According to another embodiment, compounds of formula I have the Z configuration wherein R1 and R3 are hydrogen, and R2 and R4 are selected from the group consisting of 4-Cl, 4-F and 4-Br. Such compounds include, for example, (Z)-4-chlorostyryl-4-chlorobenzylsulfone; (Z)-4-chlorostyryl-4-fluorobenzylsulfone; (Z)-4-fluorostyryl-4-chlorobenzylsulfone; (Z)-4-bromostyryl-4-chlorobenzylsulfone; and (Z)-4-bromostyryl-4-fluorobenzylsulfone.
According to another embodiment, the cytoprotective xcex1,xcex2 unsaturated aryl sulfone compound is a compound of the formula VI: 
wherein
R1, R2, R3, and R4 are independently selected from the group consisting of hydrogen, halogen, C1-8 alkyl, C1-8 alkoxy, nitro, cyano, carboxyl, hydroxyl, and trifluoromethyl.
In one embodiment, R1 in formula VI is selected from the group consisting of hydrogen, chlorine, fluorine and bromine; and R2, R3 and R4 are hydrogen.
According to yet another embodiment, the cytoprotective xcex1,xcex2 unsaturated aryl sulfone compound is a compound of the formula VII: 
wherein
Q3, Q4 and Q5 are independently selected from the group consisting of phenyl and mono-, di-, tri-, tetra- and penta-substituted phenyl where the substituents, which may be the same or different, are independently selected from the group consisting of halogen, C1-C8 alkyl, C1-C8 alkoxy, nitro, cyano, carboxy, hydroxy, phosphonato, amino, sulfamyl, acetoxy, dimethylamino(C2-C6 alkoxy), C1-C6 trifluoroalkoxy and trifluoromethyl.
According to one sub-embodiment of formula VII, the cytoprotective xcex1,xcex2 unsaturated aryl sulfone compound is a compound of the formula VIIa: 
wherein
R1 and R2 are independently selected from the group consisting of hydrogen, halogen, C1-C8 alkyl, C1-8 alkoxy, nitro, cyano, carboxyl, hydroxyl, and trifluoromethyl; and
R3 is selected from the group consisting of unsubstituted phenyl, mono-substituted phenyl and di-substituted phenyl, the substituents on the phenyl ring being independently selected from the group consisting of halogen and C1-8 alkyl.
Preferably, R1 in formula VIIa is selected from the group consisting of fluorine and bromine; R2 is hydrogen; and R3 is selected from the group consisting of 2-chlorophenyl, 4-chlorophenyl, 4-fluorophenyl, and 2-nitrophenyl.
A preferred cytoprotective styryl sulfone according to formula VIIa is the compound wherein R1 is fluorine, R2 is hydrogen and R3 is phenyl, that is, the compound 2-(phenylsulfonyl)-1-phenyl-3-(4-fluorophenyl)-2-propen-1-one.
By xe2x80x9cdimethylamino(C2-C6 alkoxy)xe2x80x9d is meant (CH3)2N(CH2)nOxe2x80x94wherein n is from 2 to 6. Preferably, n is 2 or 3. Most preferably, n is 2, that is, the group is the dimethylaminoethoxy group, that is, (CH3)2NCH2CH2Oxe2x80x94.
By xe2x80x9cphosphonatoxe2x80x9d is meant the group xe2x80x94PO(OH)2.
By xe2x80x9csulfamylxe2x80x9d is meant the group xe2x80x94SO2NH2.
Where a substituent on an aryl nucleus is an alkoxy group, the carbon chain may be branched or straight, with straight being preferred. Preferably, the alkoxy groups comprise C1-C6 alkoxy, more preferably C1-C4 alkoxy, most preferably methoxy.